SCIENCE MAY TAKE BITE OUT OF SKEETERS

Mosquitoes have the molecular equivalent of a smart bomb technology that guides them to human targets, Yale University researchers reported Thursday in the journal Nature.

The scientists for the first time have found a smell receptor in mosquitoes that responds to a single chemical in human sweat, which in theory alerts mosquitoes that a Homo sapiens blood buffet is nearby and open for feasting.

Scientists may be able to capitalize on the findings and develop a better mosquito repellent or mosquito trap, said John Carlson, professor of molecular, cellular and developmental biology at Yale and senior author of the paper.

"If the mosquito uses the receptor to find people, then maybe we can make a repellent that stops the receptor from working," Carlson said.

Humans have more than a dozen chemicals in their sweat that are attractants for mosquitoes, but the genetic mechanisms used by the insects to find their targets have been unknown.

Carlson and his colleagues investigated the gene AgOr1, which is part of the olfactory system of females of the species Anopheles.

The Anopheles mosquito transmits malaria, which kills more than 1 million people a year.

The gene was placed in the fruit fly Drosophila and the mutant flies responded strongly to 4-methylphenol, a chemical in human sweat known to attract mosquitoes.

"Once you know the molecular system, you might be able to come up with agents that will block the system from working, that can jam the system," Carlson said.

And, he added, as more is known about how mosquitoes are attracted to specific targets, more effective traps might be developed.

"What they did is pretty neat. It hasn't been done before," said Theodore Andreadis, chief medical entomologist at the Connecticut Agricultural Experiment Station in New Haven, Conn.

"But how important it is in the whole realm of how mosquitoes find a host, that may be somewhat trivial."

For instance, human sweat contains about 16 known mosquito attractants and the one identified by Yale researchers is not the most potent, Andreadis said.

Carlson agreed more study is needed before optimum benefits of the research are realized.

"The best repellent would probably be a cocktail" of different agents that block a host of attractants, agreed Carlson.

Such research is important, he said.

"Malaria is a huge world health threat," Carlson said.

"And the most effective way to control malaria is to control the insects that spread it," he said.

BUILDING A BETTER REPELLENT?

The scientists for the first time have found a smell receptor in mosquitoes that responds to a single chemical in human sweat, which in theory alerts mosquitoes that a Homo sapiens blood buffet is nearby and open for feasting. Scientists may be able to capitalize on the findings and develop a better mosquito repellent or mosquito trap.

William Hathaway is a reporter for the Hartford Courant, a Tribune Publishing newspaper.